Strain relief



Oct. 29, 1940. H R, GORDON ET AL 2,219,545

STRAIN RELIEF Filed Oct. 6, 1939 /1 ROY G ORDO/V FHA NC/S r? FL 0R SHE/MI/VVE/VTORS PR ATTORNEY Patented Oct. 29, 1940 UNITED STATES PATENTOFFICE STRAIN RELIEF Harold Roy Gordon, Flossmoor, and Francis F.Florsheim, Chicago, Ill., assignors to Diamond Wire v8r Cable Co.,Chicago Heights, 111., a corporation of Illinois Application October 6,1939, Serial No. 298,254 3 Claims. (01. 173322) This invention relatesto an improved strain relationship to some other part of an electricalrelief and has, for one of its principal objects, apparatus oralternatively for preventing undue the provision of means whereby unduestrains pulls on lengths of rope, cord or similar elements.

and pulls on electrical conductors such as in- Figure 8 shows a modifiedform of the invensulated wires will be automatically taken care of tion.5

and undesirable results from such pulls and As shown in the drawing:strains eliminated. The reference numeral ii! indicates generally One ofthe principal objects of this invention a piece of relatively stiff yetsomewhat flexible is to provide a simple and economical, yet efimaterialwhich forms the body portion of the 10 cient device, for the relief andelimination of improved strain relief of this invention. Ordinary 10undue strains and pulls on wires and similar commercial fiber has beenfound to be quite suitstructures such as cords, ropes or any relatedable for this purpose although other materials elements. may be employedwith considerable success.

A further object of the invention resides in the In its preferred form,the improved strain reproduction of a strain relief device which canlief comprises a length fiber, preferably 15 be readily manufactured incommercial quantities rectangular in shape, as shown in Figure l. and atrelatively low prices and which can be ashaving a plurality of openingspunched or othersembled with the wire and related structures Wise formedtherein, there being four openings with a minimum expenditure of timeand labor. for rivets or some other fastening elements, these A stillfurther object of the invention is to openings being designated at 2 andbeing of a 20 provide a strain relief for electrical conductors size toreceive suitable rivets or bolts.

which will meet the requirements of all the At the middle of the lengthof fibrous material underwriters laboratories and comprise a safe it isprovided a scored line as shown at it whereand foolproof installation.by the length of material it may be bent and Other and further importantobjects of the doubled upon itself, preferably without breaking. 25invention will be apparent from the disclosures There is likewiseprovided in the length in the accompanying drawing and followingmaterial it two openings it which are for the specification. passage ofthe insulated wire or other length of The invention, in a preferredform, is shown material therethrough. in the drawing and hereinaftermore fully de- It will be noted that when the plate it is 3() scribed.doubled upon itself, the openings iii are offset In the drawing: withrelation to each other as best shown in Figure 1 is a top plan View ofthe improved Figure 2, and the wire 18 or other material to be strainrelief device of this invention, showing the held against undue pulls orstrains is passed same in one piece and before assembly. through one ofthe openings i8, thence between 35 Figure 2 illustrates the strainrelief of this the two adjacent parts ill of the strain relief inventionassembled on a wire and ready for initself and finally out the otheropening l6 as stallation in some electrical apparatus such as a moreclearly indicated in Figures 5 and '7. radio receiver or the like. Thetwo adjacent plate portions Ill could then 40 Figure 3 illustrates a mfie form of the be fastened together by rivets or the like 20 which 40vention shown in Figure l and wherein the depass through the alignedopenings i2, and the V is produced in two p The Opening wire isaccordingly held in securely gripped posithe Wire is Sh wn a O aSlightly fi t D tion between the plate elements it] and without Figure 4WS a further modification 0f the any possibility of its being pulled outof place structure of Figure 3. or even being turned by twisting action.Ob- 45 Figure 5 illustrates the strain relief of this inviously, whenthis strain relief element ill with vention assembled against a panel orpart of a the associated wire is either placed against or radio cabinet.pulled against some relatively fixed element, any Figure 6 illustratesin more detail the assembly further pull on the wire is immediatelytransof the strain relief of this invention in some sort mitted throughthe strain relief to the fixed ele- 50 of electrical appliance such asthe ordinary radio ment, and damage to the wire or electricalconreceiver or the like. nections is avoided. In the case of ropes,cords, Figure '7 is a side elevation, illustrating the strings and thelike, this same action occurs. strain relief of this invention appliedto a length In Figures 3 and 4, modifications of the inof wire forapplication in almost any desired vention are illustrated in whichsingle plates 30 55 and 32 respectively are provided, the plate 30 beingadapted for association with a similar plate having a circular opening34 therein, and the same strain relief action takes place by riveting orbolting the two associated plates together by passing such rivets orbolts through the openings 36 provided for this purpose.

In Figure 4, a pair of square openings 38 is shown, and this structureacts in the same manner in that openings of various sizes and shapes canbe used, depending somewhat upon the size, shape and consistency of thewires, cords,,conductors or elements to be used with the particularstrain relief.

In Figure 5, a pair of plates such as those shown at 30 in Figure 3 areillustrated as sustaining a wire IS in strain relief position againstone face of a board or panel 40 which may comprise a portion of someelectrical equipment such as a radio receiving cabinet or the like. Thewire i8 is passed through one opening in the first plate 30 and thencebrought across and through the other opening in the adjacent similarplate and finally out to an opening 42 in the plate or panel 40. In thiscase, bolts M can be provided which pass through the openings in theplates 30 and thence through further openings in the panel board orsupport 46 and are finally fastened in place by means of nuts 45 whichare pulled down sufiiciently to provide a suitably gripping action onthe wire l8. Obviously, screws may be used instead of bolts, or someother fastening means may be employed.

A clearer view of such in Figure 6 wherein the duced as also the strainrelated wire l8 with its terminals fastened to binding posts or the like59, and this illustration shows more clearly the safety action of thestrain relief of this invention in that there is practically nopossibility of the ends of the wire .18 being pulled away from therespective binding posts which would, of course, put the particularapparatus out of commission and, perhaps, cause an accident.Furthermore, in the use of this construction, undue twisting action onthe wire is prevented, particularly at any portion of the wire beyondthe strain relief.

In Figure 8, the rope or wire is shown mounted in a single plate havinga plurality of openings a structure is illustrated panel board 40 isreprorelief plates 38 and the 62 therein, preferably three or more, andthe rope or wire is threaded through these openings as shown in a mannerto produce a snubbing or strain relief arrangement.

bending, the plate It will be evident that herein is provided a verysimple yet quite efficient strain relief for electrical conductors,ropes, cords and the like, and which can be readily applied and willpractically never get out of order or lose its efiiciency even under themost adverse conditions 'of use or abuse. It will further be obviousthat the invention may be applied in other fields without any particularchanges in structure except, perhaps, relative dimensions and that thedevice can be made and used in one or two parts with equal satisfaction.

Also, it will be evident that in the constructions shown in Figures 3and 4, a single set of dies or punches may be used to produce the plateelements 30 and 32 respectively, and that, in assembling these plates onwires or cords, all that is necessary is to reverse one plate so thatthe gripping openings will assume the desired staggered relationship.

We are aware that many changes may be made and numerous details ofconstruction varied throughout a wide range without departing from theprinciples of this invention, and we, therefore, do not purpose limitingthe patent granted hereon otherwise than as necessitated by the priorart.

We claim as our invention:

1. A strain relief, comprising a fibrous plate transversely scoredadjacent its middle for ready bending, the plate having a pair ofsimilar openings therein, said openings arranged for offset relationshipwhen the plate is bent and doubled upon itself.

2. A strain relief, comprising a fibrous plate transversely scoredadjacent its middle for ready having a pair of similar openings therein,said openings arranged for offset relationship when the plate is bentand doubled upon itself and provided for the retentive reception of anelectrical conductor.

3. In combination, a conductor and a strain relief therefor, comprisinga fibrous plate transversely scored adjacent its middle for readybending, the plate having a pair of similar openings therein, saidopenings arranged for offset relationship when the plate is bent anddoubled upon itself and provided for the retentive reception of theconductor when fitted into the plates and through the openings.

FRANCIS F. FLORSHEIM. H. ROY GORDON.

